This invention relates to a method of packing an article by means of a heat shrinkable film.
A polyethylene film which has been elongated in one or two directions has a property of shrinking a predetermined amount when it is heated so that it is used to pack articles of various shapes by utilizing its heat shrinkable property.
For example, this method of packing is applied for packing a large coil of wide paper such as newspaper, and a pallet supporting articles stacked thereon in a plurality of stages or layers.
Such packing is generally performed in the following manner. Thus, a sheet of the heat shrinkable film shaped to cover an article to be packed is placed on the article such as a paper coil or a pallet carrying articles, then the assembly is passed through a heated oven to cause the sheet to shrink and pack the article.
However, this method accompanies the following defects. More particularly, it is necessary to perform the heat shrinkable film into a bag suitable to contain the article to be packed. This requires the step of preparing the bag, so that where it is desired to pack articles of different size and configuration, it is necessary to prepare and stock a variety of bags.
Such packing can also be accomplished by mounting a sheet of the heat shrinkable film on an article to be packed, forming the sheet into a bag surrounding the article and then causing the bag to heat shrink thereby packing the same.
In some cases, the oven for effecting the heat shrink is large requiring a large cost of installation. Such large oven requires a large quantity of heat to initially raise the temperature and to maintain the operating temperature thus increasing the cost of packing.
In an alternative method, a heat shrinkable film is wrapped about an article to be packed under a suitable tension so as to pack the article by the compressive force created by shrinkage. However, this method is difficult to adequately wrap the film and the compressive force is not uniform.